EGFR Inhibitor Enhances Cisplatin Sensitivity of Oral Squamous Cell Carcinoma Cell Lines

Epidermal growth factor receptor (EGFR) is involved in multiple aspects of cancer cell biology. EGFR has already been identified as an important target for cancer therapy, with various kinds of EGFR inhibitors currently used in treatment of several human cancers. Recently, EGFR and its downstream signaling pathways were identified as being associated with cisplatin sensitivity. In addition, EGFR inhibitors have shown significant promise for patients who failed cisplatin-based therapy. In this study, we investigated whether treatment with an EGFR inhibitor improves cisplatin sensitivity in oral squamous cell carcinoma (OSCC) cell lines. The effects of a combination of AG1478, a specific EGFR tyrosine kinase inhibitor, with cisplatin were evaluated in cultured OSCC cell lines and cisplatin-resistant sublines. Higher expression of EGFR and p-EGFR was found in the two cisplatin-resistant cell lines compared with the corresponding parental cell lines. In addition, augmented inhibition of OSCC cell growth by the combination of AG1478 with cisplatin was found in both cell lines. These results suggest that the combination of an EGFR inhibitor and cisplatin may be useful as a rational strategy for the treatment of patients with oral cancer with acquired cisplatin resistance

Chemokine receptors CXCR4 and CCR7 promote metastasis by preventing anoikis in cancer cells

Chemokine receptors are essential mediators of the metastatic spread in various cancer types; however their precise function in the development of secondary tumors remains poorly understood. We report here a novel property of the chemokine receptors CXCR4 and CCR7 in inhibiting detachment-induced cell death – anoikis, which is believed to be one of the major blocks in the metastatic spread of various neoplasms. Activation of these chemokine receptors by their respective ligands, CXCL12 and CCL21 specifically reduced the sensitivity of metastatic breast cancer cells to anoikis by a distinct mechanism of selective regulation of pro-apoptotic Bmf and anti-apoptotic Bcl-xL proteins. Consequently, functional CXCR4 and CCR7 increased cell survival in the absence of correct ECM attachment both in vitro and in vivo. We also demonstrated that preventing chemokine-induced reduction in Bmf levels significantly attenuated breast cancer metastasis in an experimental mouse model. These results provide evidence for a previously unknown axis in malignant tumors, which connects chemokine receptors with deregulated apoptosis in the absence of the appropriate cell – ECM interaction and may offer novel targets for therapeutic intervention for the treatment of metastatic breast and potentially other tumors.M Kochetkova, S Kumar and S R McCol

Highly passage of Spodoptera litura cell line causes its permissiveness to baculovirus infection

It is well known that the characteristics of cell lines possibly alter when cell lines are at high-passage number because of the environmental selection. We do not know whether non-permissive or low-permissive cell lines could become permissive or more permissive to virus infection after over-high passage. In the present studies, the alteration of the permissiveness of Spodoptera litura cell line Sl-zsu-1 to three baculovirus infection was investigated after over-high passage, and the possible mechanisms are also investigated. Vigorous apoptosis in Sl-zsu-1 cells was induced by both the recombinant Autographa californica multiple nucleopolyhedrovirus AcMNPV-GFP-actin and the celery looper Anagrapha falcifera multiple nucleopolyhedrovirus AfMNPV, suggesting the replication of the two viruses was blocked by apoptosis. However, the cells infected by S. litura multicapsid nucleopolyhedrovirus SpltMNPV did not undergo apoptosis, but the SpltMNPV titre of the supernatant was not detectable, suggesting this cell line was low-permissive for this virus infection and other factor(s) involved in blockage of the virus replication except apoptosis. However, when Sl-zsu-1 cells had been subcultured continuously for more than 4 years (high-passage cell), which was named as Sl-HP cell line afterwards, no significant apoptosis was induced by the three baculovirus in Sl-HP cells, and many replicated virions or nucleocapsids were observed in the cells. But the permissiveness of Sl-HP cells to the three viruses was very different according to the titre of viruses in the cell cultures. Interestingly, the DNA extracted from SpltMNPV could induce vigorous apoptosis of Sl-HP cells. Altogether, Sl-zsu-1 cell line becomes more permissive to baculovirus infection after over-high passage and multiple paths can block the baculovirus infectivity